Where I live, we call this a reference letter. It would be signed by your boss. It would say where you worked, what your job title was, how long you worked there, and whether your work was satisfactory. Your boss would write it and sign it.
Where you live, does the employee usually write this, and then ask the boss to sign it?
This is to certify that Mr. ......................................, Son of .......................................... worked as Senior Executive in our company from .............................. to ............................ with our entire satisfaction. During his working period we found